The present invention relates to a brake mechanism for a wheeled vehicle supported on parallel members, and, more particularly, for a gondola car loader such as the one shown in FIG. 1.
To facilitate an understanding of the present invention and its preferred application, the gondola car loader will be described generally. In FIG. 1 a gondola car loader is indicated generally by the numeral 10. The device is particularly useful for loading and unloading gondola railroad cars, such as gondola car 12, positioned adjacent one another along a railroad track. The gondola car loader may include a chassis 14 movable along the top edges of adjacent gondola cars in the direction of the railroad track 16 on which the cars are located. Four beams, such as beams 18 and 20, pivotally mounted near their centers to the chassis 14, may each carry wheels for engaging the top edges of the cars. Advantageously, each beam carries a wheel at both ends. As shown in FIG. 1, for example, the beam 18 is mounted for pivoting about the pivot point 22 and carries wheels 24 and 26 at either end. The beams are adapted to be pivoted to selectively engage the wheels with the top edges of immediately adjacent cars to support the chassis 14, thereby facilitating motion of the chassis across the gaps between adjacent cars. A knuckle boom 28, for loading and unloading cargo from the cars, may be rotatably mounted to the chassis 14.
The gondola car loader such as shown in FIG. 1 was developed for the applicant herein and is described in greater detail in applicant's U.S. Pat. Nos. 4,096,954 and 4,099,635.
Initially the gondola car loader was equipped with a braking mechanism such as that shown in FIGS. 2A and B. This braking mechanism was provided to secure the gondola car loader in position at times when the gondola car loader was not being moved along the tops of the gondola cars, particularly, at times when the knuckle boom was being employed to load and unload the gondola cars. Also, in situations where the gondola car loader was being used on a moving train, the braking mechanism could prevent unwanted motion of the gondola car loader caused by variations in the speed of the train.
The original gondola car loader braking apparatus included an outer brake shoe mechanism such as shown in FIG. 2A and an inner brake shoe mechanism such as shown in FIG. 2B.
Referring first to FIG. 2A, the outer brake shoe mechanism comprised a hydraulic ram 42 having a cylinder 44 and a piston rod 46. The cylinder 44 was connected to an outer brake shoe 48 and the piston rod 46 was connected to a second outer brake shoe 50 for engaging the opposite side wall of the gondola car 54. The braking mechanism was rigidly connected to the chassis 56 of the gondola car loader by means of sleeves 58 and 60 attached to longitudinal chasis members 62 and 64, respectively.
Referring now to FIG. 2B, the inner brake shoe mechanism included a first inner brake shoe and arm assembly 41 and a second inner brake shoe and arm assembly 43. A shoe portion 45 of the assembly is shown contacting an inner side of the wall 52 of the gondola car. The assemblies 41 and 43 are respectively connected to hydraulic rams 47 and 49 for pivoting about axes 51 and 53. For clarity, the hydraulic ram 47 is shown in an extended position wherein the shoe portion 45 of the assembly 41 engages with the wall 52 of the gondola car, and the hydraulic ram 49 is shown in a retracted position, wherein the shoe 45' of the second assembly 43 is out of contact with the wall 54 of the gondola. Normally, however, the hydraulic rams 47 and 49 would both be in their extended positions to effect braking, or in their retracted positions to move the assemblies 41 and 43 upward and away from the gondola car.
The braking mechanism 40 shown in FIGS. 2A and B was capable of providing braking action for the gondola car loader, but had a number of disadvantages, the most significant of which were that it required three hydraulic rams to activate the brake shoes, that it lacked rigidity, and that it interferred with movement of the loader from gondola car to gondola car.
Accordingly, it is an object of the present invention to provide a sturdy, inexpensive and easily fabricated braking mechanism, particularly suited for use with a gondola car loader.
Applicant devised the present invention which employs two pairs of braking shoes, a first pair being adapted to clamp one side wall of the gondola car, and the other pair being adapted to clamp the other side wall of the gondola car. The braking mechanism of the present invention is sturdier in construction, does not interfere with the movement of the loader and the braking mechanism is self-centering and provides clamping action which facilitates the straightening of bowed or otherwise irregularly shaped side walls often found on gondola cars.
The prior art contains brake mechanisms which employ pairs of brake shoes to clamp members on which a vehicle rides, to provide braking action. Such brake mechanisms are shown in U.S. Pat. No. 708,837 to Sebastian, U.S. Pat. No. 1,650,456 to Lorenze, and U.S. Pat. No. 2,856,030 to Snow, Jr. However, all of these prior art braking mechanisms are adapted for use for vehicles traveling on parallel rails such as railroad tracks and are not adapted for use on rails or members having an irregular shape. They are not, therefore, intended for use in straightening irregularly shaped members over which they ride. Finally, these prior art braking mechanisms are not adapted for use in the particular environment of a gondola car loader. The gondola car loader is adapted to move from gondola car to gondola cars, and in order to accomplish this, the gondola car loader must "walk" across gaps between adjacent gondola cars. Typically, gondola cars have end walls which are nearly the same height as the side walls on which the gondola car loader rides. If the inner brake shoes of the braking mechanism extend downward alongside the upper edges of the gondola car side walls, the inner shoes would impact the end walls of the gondola car and arrest the motion of the gondola car loader as it attempted to move across the gaps between adjacent gondola cars. Thus a conventional braking mechanism with inner brake shoes of fixed height would be unuseable on a gondola car loader.
Accordingly, it is an object of the present invention to provide a braking mechanism for a vehicle moveably supported on irregularly shaped but generally parallel members.
It is yet another object of the present invention to provide a braking mechanism for use with a vehicle adapted to be moveably supported on the upper edges of adjacent gondola cars.
While the above-mentioned prior art braking mechanisms employ pairs of braking shoes to clamp parallel members on which their vehicles ride, all of the prior art patents cited employ relatively complex mechanisms in order to move pairs of brake shoes in opposition simultaneously. Specifically, the Sebastian patent requires a manually rotated pair of double acting cams to actuate the brake shoes. In the Lorenze patent, as shown best in FIG. 2, the braking mechanism disclosed requires a pair of hydraulic rams and a complex scissors action mechanism to simultaneously actuate the pairs of brake shoes. Finally, the Snow, Jr., patent, as shown in FIG. 6 thereof, employs a sequence of four relatively massive levers 15 and 16 pivoted at points 22, 17, 50 in order to actuate the pairs of brake shoes.
None of the above cited patents disclose a floating brake mechanism or one that is capable of centering itself on irregularly shaped, generally parallel members on which a vehicle rides.
Accordingly, it is another object of the present invention to provide a simply and inexpensively fabricated vehicle brake, employing two pairs of brake shoes and a single hydraulic ram to clamp parallel members on which the vehicle is moveably supported.
It is yet another object of the present invention to provide a self-centering, floating braking mechanism employing two pairs of brake shoes for use on a vehicle adapted to ride on irregularly shaped supporting members which are also irregularly spaced but generally parallel.
These and other objects and features of the present invention will become apparent from the claims and from the following description when read in conjunction with the accompanying drawings.